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Can municipally supplied treated seawater for toilet flushing be used as a strategy for earning WEp1 and WEc1 Water Use Reduction?

Inquiry

Can municipally supplied treated seawater for toilet flushing be used as a strategy for earning WEp1 and WEc1 Water Use Reduction?

Ruling

No, municipally supplied sources of non-potable water, including seawater, are not applicable to the WE fixture water use reduction credits, including WEp1 (D+C, EBOM) and WEc1 (CI) Water Use Reduction, or considered graywater. As stated in LI 1551 (12/12/2006) This credit focuses on fixture efficiency and on-site water reuse. In addition, the Water Use Reduction Additional Guidance document (updated 8/16/2010, http://www.usgbc.org/ShowFile.aspx?DocumentID=6493), confirms that the focus of the prerequisite is water efficiency of the installed fixtures, regardless of the water source, and only on-site water reuse is available as an alternative compliance path.
However, municipally treated wastewater (including treated seawater) applies to SSc1 - Path 9 Innovative Wastewater Technologies (CI), WEc2, Innovative Wastewater Technologies (BD+C), and can be used if the two conditions of LEED Interpretation 10117 are met: 1) the seawater is municipally supplied or explicitly approved by the municipality and 2) meets all applicable codes and permitting requirements, so as not to contaminate the municipal wastewater system with high salinity. For EBOM projects, where no wastewater credit is available, the project may apply for innovation credit for use of this strategy.

**Update October 1, 2013: Note that LEED Interpretation 10117 has been updated to clarify that seawater must be treated to appropriate levels for non-potable uses in order to apply to WEc2 Innovative Wastewater Technologies; seawater that is treated to potable drinking water standards would not apply. Any on-site energy use to desalinate the seawater must be included in the EAp2/c1 calculations. Refer to the guidance document. Applicability of Seawater in Water Efficiency credits also updated.

The installation of bedside patient care units, which is a combined toilet and lavatory, is required for some patient rooms. Can the patient care unit be excluded from the calculations since there ar...

Inquiry

The installation of bedside patient care units, which is a combined toilet and lavatory, is required for some patient rooms. Can the patient care unit be excluded from the calculations since there are no low-flow options available?

Ruling

All fixtures that are covered by the EPAct 1992 must be included in the credit calculations, even if there are no low-flow options available. The use of these fixtures by only the patients in a limited area can be factored into the calculations.

Can untreated groundwater, unsuitable for drinking, contribute towards WE credits 1, 2, and 3 as a non-potable water source for irrigation and sewage conveyance?

Inquiry

Can untreated groundwater, unsuitable for drinking, contribute towards WE credits 1, 2, and 3 as a non-potable water source for irrigation and sewage conveyance?

Ruling

This approach does not meet the intent of the WE credits. Although the local groundwater may not be suitable for drinking straight out of the ground, it still represents an important source of potable water. Applicable internationally.

Our project has made water efficiency a high priority and has elected to install 0.5 GPM flow restrictors with occupancy sensors on all lavatory faucets, waterless urinals and dual flush toilets throu...

Inquiry

Our project has made water efficiency a high priority and has elected to install 0.5 GPM flow restrictors with occupancy sensors on all lavatory faucets, waterless urinals and dual flush toilets throughout. In our analysis regarding whether to continue our application under the LEED CI version 2 system or switch over to LEED CI v2009, we were surprised to find out that we would not be able to reach the 30% threshold and would therefore not be able to achieve any points for WEc1 under the version 2009 system, despite the fact that we have selected some of the most efficient fixtures available on the market. Using the fixtures listed above, we are able to achieve 45.9% savings under the v2 system, but only 29% savings under the new system due to the fact the baseline flow rate for lavatories under the v2009 system is 0.5 GPM instead of 2.2 GPM. In essence, the bar is set higher under the new system, but the baseline flow rate for lavatories is also much more stringent, making it near impossible to achieve points under this credit without the use of composting toilets, gray water systems or rainwater systems - which are not allowed by high rise buildings in our area. We have two questions: 1) Given the fact that it will be near impossible for the majority of LEED CI project to achieve points for WEc1 under the v2009 system despite selecting the most efficient fixtures on the market, we'd like to ask the USGBC to reconsider the threshold for achieving points, particularly since the baseline for faucets in v2009 changed significantly. We suggest lowering the first v2009 threshold for points to 25% water savings which would allow projects that use 1/8 gallon, high efficiency urinals to potentially earn points. An alternative solution would be to use the same baseline as version 2, while keeping the raised v2009 threshold at 30% savings. 2) If you are not willing to reconsider the threshold or adjust the baseline for faucets, please advise how we might achieve points for WEc1 under the v2009 system in cases where composting toilets, gray water systems and rain water catchment system are not allowed. Keep in mind we're already using 0.5 GPM flow restrictors and occupancy sensors on all faucets, waterless urinals and dual flush toilets throughout.

Ruling

The project is requesting the USGBC to revise the thresholds that have been established for the LEED-2009 rating system. The model plumbing codes requires .5 GPM or .25 GPC for public use (See footers of LEED 2009 Design and Construction Reference Guide). Part of the goal of the LEED rating system is to transform the marketplace towards a more sustainable building practice. As the market transforms and old best practices become standard practice, LEED also continues to evolve and raise the bar to continue its mission of transforming the marketplace towards a more sustainable built environment. LEED credits are established through a collaborative and iterative process of many stakeholders, opened for public comment, and balloted and approved by the USGBC member organizations. Those who wish to make changes to the rating system are encouraged to become involved in that process. If the project team is limited by code requirements, scope of project or other restrictions from implementing strategies that will allow the project to achieve additional points under Water Efficiency Credit 1 for LEED 2009, than the project may be unable to pursue those additional credits. Given the varying scope of projects, not all credits may be achievable for all projects. Furthermore, it appears that the design team has not considered the alternative baseline for commercial faucets, that of 0.25 gallons per cycle. The consideration of this baseline allows for other technology avenues for water use reduction. It should be noted that the purpose of the Water Efficiency credits is to reduce the Volume of potable water consumed. Volume is dependent upon two variables, flow rate and time (V=RT). In addition to a focus on volume, several strategies that control the time factor are also available. Finally, dual-flush toilets are a behavioral solution representing only one technology path out of many that could yield savings over the baseline, all of which are non-behavioral and subject to independent timed controls. Applicable Internationally.

We are seeking clarification on the use of municipally provided non-potable water for achieving WEc3 under the LEED NC version 2.2 rating system. Use of municipally supplied non-potable water meets th...

Inquiry

We are seeking clarification on the use of municipally provided non-potable water for achieving WEc3 under the LEED NC version 2.2 rating system. Use of municipally supplied non-potable water meets the intent of limiting or eliminating the use of potable water and reduces the burden on municipal water supplies. However, currently, the Reference Guide does not give clear direction with concern to WEc1, WEc2 & WEc3 and municipally supplied water: WEc1 states that water savings can be claimed through the use of "water treated and conveyed by a public agency specifically for non-potable uses." WEc2 states that water savings can be claimed through the use of "municipally treated wastewater." WEc3, however, makes no statements as to whether municipally supplied recycled water can count towards water saving calculations. However, the synergies between WEc2 and WEc3 calculations leads one to conclude that municipally supplied wastewater can be used for both credit calculations. Our project will be using municipally supplied non-potable reclaimed water for both irrigation and sewage conveyance (toilet flushing). Can you please clarify whether municipally supplied reclaimed water can be used to achieve both WEc3.1 and WEc3.2?

Ruling

Municipally reclaimed water is not applicable to WEc3 achievement. This credit focuses on fixture efficiency and on-site water reuse. Applicable Internationally.

Summary: Interpretation ruling pertaining to establishing the calculation baseline for Water Reduction Credits 3.1 & 3.2 when on-site tests have been conducted, and demonstrate that the supply wat...

Inquiry

Summary: Interpretation ruling pertaining to establishing the calculation baseline for Water Reduction Credits 3.1 & 3.2 when on-site tests have been conducted, and demonstrate that the supply water pressure levels (psi) to the fixtures are substantially below the 80 psi referenced within the Energy Policy Act of 1992. Context: The scope of the project incorporates new construction of four residential halls on a college campus, which house more than 250 students and staff. Three of the buildings are three stories, and the other is four stories. Description: The residence halls are incorporating a range of fixtures that are below the flow rates within the Energy Policy Act of 1992 (dual flush toilets, and faucets within the kitchens, kitchenettes, bathrooms & apartments). The showers in the residence hall are the largest water consumer (by a large %) within the residence hall buildings. To begin to understand the water amount actually used on the project, the owner conducted some initial on-site tests to determine the supply pressure to the plumbing fixtures, and how that translated into the actual flow. On-site tests for one of the buildings have been conducted on the flow rates of the shower heads with the following results: Fixture type currently installed = 2.5 gpm 1st floor: 52 psi static, 2.10 gpm 2nd floor: 46 psi static, 1.92 gpm 3rd floor: 41 psi static, 1.79 gpm 4th floor: 37 psi static, 1.85 gpm Question: o Would the design case account for the lower psi (reduced water use) by multiplying the 'Water Use' column within the calculation template by the percentage of supply/baseline? For example for a shower on the first floor the 'Water Use" would be multiplied by 65% (52/80) or by just including 2.10 gpm as the flow rate for the fixture on this floor? o What is the appropriate methodology for establishing the calculation baseline when the water pressure supply rate (psi) is substantially lower than the 80 psi outlined as the baseline flow rates under the Energy Policy Act of 1992?

Ruling

[Note: this ruling was revised on 9/1/04.] The underlying assumptions used for calculating projected water use savings should remain consistent between the baseline and design case. Supply water pressure varies across the United States and within individual buildings (as you note in your inquiry). Flow rates at 80 psi are used for the calculations in this credit for consistency and to reward use of efficient fixtures. It is recommended that all projects use the flow rates reported by the manufacturer at 80 psi for comparison with the Energy Policy Act of 1992 flow rates. If you wish to use on-site tests to report the most accurate volume of water use, you must be consistent throughout all fixtures and test both baseline and design fixtures. It is not acceptable to use flow rates at 80 psi for some fixtures and actual flow rates for other fixtures. Measurement can also be used to account for the benefits of whole-building strategies, e.g., flow restrictors at the water service entrance. Applicable Internationally.

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